Friday, July 9, 2010


What is Jogger’s Foot (Medial Plantar Neuropraxia)?

Jogger’s foot, otherwise known as medial plantar neuropraxia, is a chronic entrapment syndrome of the medial plantar nerve in the foot. It is an unusual cause of heel pain in long distance runners.


Who get’s Jogger’s Foot?
Jogger’s foot is seen in athlete’s that participate in running endurance sports such as marathons, ultramarathons and Iron Man competitions as well as any athlete that is repetitively training with long distance running. A runner with flat feet is more predisposed to this injury than someone with a more pronounced longitudinal arch of their foot. Medial plantar nerve entrapment has also been seen in an unusual presentation in ballet dancers.


What is the relevant anatomy of this region?
The medial plantar nerve is a small nerve that supplies sensation to part of the bottom of the foot. It branches off of the much larger posterior tibial nerve above and behind the ankle on the medial (or inside) aspect of the ankle. The medial plantar nerve travels beyond the ankle and curves under the medial border of the foot. It enters a tunnel behind a bony prominence, known as the navicular. This tunnel is also bordered by a small muscle known as the abductor hallucis muscle which originates from the heel and inserts on the great toe. Repetitive trauma and inflammation caused by long distance running leads to swelling and compression of the medial plantar nerve in this tunnel. This effect is exacerbated by a flat arch and foot (known as pes planovalgus). With a poor arch, more pressure and stretch is placed on this nerve since the foot contacts the ground with higher force.

How is the diagnosis of Jogger's foot made?
Making this very rare diagnosis requires a high index of suspicion for this injury and awareness on the part of the treating sports medicine or foot and ankle physician specialist. In the many of cases, symptoms may be present for more than a year prior to determining the correct diagnosis. The runner describes chronic pain on the inside of the mid portion of the foot. This pain is often described as an ache in the arch region of the foot. There may or may not have been a specific injury that occurred in the past to cause the onset of pain. They may also describe a “giving-away” sensation while running. There may also relate a burning sensation in the medial aspect of the heel. This is from the irritated nerve causing chemical excitation of other nearby branches to the heel from the same posterior tibial nerve. On physical exam of the injured foot, there will be tenderness with palpation over the area of nerve entrapment just behind the navicular bone on the medial side of the foot along the arch. Tapping this area, otherwise known as a Tinel’s test, will recreate the athlete’s symptoms as the nerve is irritated. It is important that the alignment of the foot and heel are evaluated for the longitudinal arch.

How is Jogger's foot treated?
Once the diagnosis of jogger's foot (medial plantar neuropraxia) is made, initial treatment involves changing the mechanical forces at play that lead to the nerve irritation in the first place. A period of relative rest for the foot may be necessary to allow the irritated nerve to calm down. This can include the involvement of various non-impact cross-training exercises so that the athlete may maintain their cardiovascular fitness. The runner’s shoe wear must be evaluated for medial arch support as well as overall quality. Custom arch support inserts may be useful, however in some cases they may exacerbate the symptoms by placing further pressure on the irritated nerve. A running evaluation by a specialized sports chiropractor, physiotherapist, or practitioner knowledgeable in running mechanics is necessary to alter the runner’s gait in a fashion to relieve pressure on the medial aspect of the foot. Regular anti-inflammatory use is important to decrease the body’s inflammatory response and swelling at the entrapment site. Other medications that specifically target nerve pain may be useful as well. An injection of cortisone can be considered in the region of entrapment, however the proximity of the plantar fascia, and the possibility of it’s rupture,
is always a consideration in endurance runners.

In the rare circumstance that a runner’s symptoms are not able to be alleviate with non-operative management as detailed above, then surgical treatment may be considered. This would include an incision along the medial border of the foot and the site of nerve entrapment is exposed. Part of the ligament (“naviculocalcaneal”) is released, such that the medial plantar nerve has more space surrounding it and less of a chance of further compression. Following surgery, there will be a period of relative immobilization of the foot and restriction on weight-bearing.

What is the long term prognosis of Jogger’s Foot?
The majority of runner’s with entrapment of the medial plantar nerve improve without the need for surgery. This usually requires months of non-operative treatment to alter the pressure over the area as well as retraining the athlete in their running technique. Due to the very rare nature of this injury, there are no large series of runner’s reported in the sports medicine research literature to give a specific timetable or determine the probability for full recovery.

No comments:

Post a Comment